The essential oil of agarwood had a protective effect against oxidative damage induced by hydrogen peroxide (H2O2) in PC12 cells [85]. The aqueous extract of A. crassna leaves had radical scavenging capacities determined by 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS), ferric reducing antioxidant power (FRAP), and 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) scavenging assays [68]. A methanol extract of A. crassna leaves was also found to have anti-oxidative activities [86]. The 100% (v/v) ethanol extract exhibited the highest DPPH radical scavenging activity among the 0% to 100% (v/v) ethanol extracts isolated from A. crassna young leaves [87]. β-Caryophyllene displayed strong antioxidant effects determined by the DPPH and FRAP scavenging methods [80]. Other compounds 2835, and 144, isolated from agarwood, also showed an anti-oxidative effect [8,22,27].